use a unique key to store per-thread request buffers

[ardour.git] / libs / pbd / event_loop.cc

diff --git a/libs/pbd/event_loop.cc b/libs/pbd/event_loop.cc
index 11177610030e9a694d6711961715bfac1e10f1ca..09099f7eb5b260c09da11728b56cc5918c521350 100644 (file)
--- a/libs/pbd/event_loop.cc
+++ b/libs/pbd/event_loop.cc
@@ -17,6 +17,10 @@
 
 */
 
+#include <cstring>
+
+#include <pthread.h>
+
 #include "pbd/compose.h"
 #include "pbd/debug.h"
 #include "pbd/event_loop.h"
@@ -171,24 +175,30 @@ EventLoop::pre_register (const string& emitting_thread_name, uint32_t num_reques
                   AbstractUI constructor. Note that if
                */
 
-               /* make a key composed of the emitter and receiver thread names */
+               const string key = string_compose ("%1/%2", mapping.emitting_thread, mapping.target_thread_name);
 
-               string key = emitting_thread_name;
-               key += '/';
-               key +=  mapping.target_thread_name;
-
-               /* if the emitting thread was killed and recreated (with the
-                * same name), this will replace the entry in
-                * thread_buffer_requests. The old entry will be lazily deleted
-                * when the target thread finds the request buffer and realizes
-                * that it is dead.
+               /* note that there is no cleanup mechanism to remove
+                * dead/out-of-date entries from this map.
                 *
-                * If the request buffer is replaced before the target thread
-                * ever finds the dead version, we will leak the old request
-                * buffer.
+                * the request buffers themselves will be cleaned up
+                * when the requesting thread exits (by the
+                * thread-local-storage (TLS) cleanup mechanism). 
+                *
+                * but an entry will remain in the map.
+                *
+                * really need a way to register some end-of-thread callback
+                * that will remove the entry from the thread_buffer_requests
+                * container. but there is no such thing in the pthreads API
+                *
+                * the target thread only searches the map once, when the event
+                * loop object is constructed. if it finds invalid buffers
+                * it will (a) never get any requests for them anyway (b) will
+                * find them marked "dead" and delete them.
                 */
 
                thread_buffer_requests[key] = mapping;
-               DEBUG_TRACE (PBD::DEBUG::EventLoop, string_compose ("pre-registered request buffer for \"%1\" to send to \"%2\", buffer @ %3\n", emitting_thread_name, trs->name, mapping.request_buffer));
+               DEBUG_TRACE (PBD::DEBUG::EventLoop, string_compose ("pre-registered request buffer for \"%1\" to send to \"%2\", buffer @ %3 (key was %4)\n",
+                                                                   emitting_thread_name, trs->name, mapping.request_buffer, key));
        }
 }
+